A centrifugal separator of this art is known. Thus U.S. Pat. No. 4,334,647 discloses a decanter centrifuge comprising a bowl and a conveyor with an acceleration chamber and a feed accelerator in the acceleration chamber, the feed accelerator being joined to a feed pipe and having semi-circular acceleration vanes. The bowl and feed pipe are rotated at predetermined rotational speed rates by a drive motor via respective pulleys and belts. In use a pond of feed material is formed in the bowl. The acceleration chamber extends into the pond and comprises a number of axial openings for feed material to flow from the feed accelerator, through the acceleration chamber and into the bowl forming jets. There is a risk that solids in the feed material will sediment already in the acceleration chamber thus blocking the passage into the bowl.
Generally the provision of suited feed inlets for centrifugal separators is the subject of a big number of patents. U.S. Pat. No. 5,345,255 discloses a decanter centrifuge comprising a bowl and a conveyor with an inlet chamber having an open construction in that a hub of the conveyor at the inlet chamber, or feed zone, is constituted by longitudinal ribs only, providing between them large ports for feed material introduced into the inlet chamber to flow radially into the bowl. Hereby the feed material, or liquid, is accelerated slowly in the feed zone, or inlet chamber, to the rotational speed of the conveyor. According to its description this slow acceleration is due to the lack of any accelerating surface within the feed zone. The slow acceleration causes the volume of feed in the feed zone to increase so that its centrifugal pressure forces outward movement. Due to enlarged areas through which the feed liquid can reach the level of feed material or liquid, called “the pond” (without passage through nozzles and openings which create concentrated flows or jets), turbulence is avoided in the pond at the feed zone.
U.S. Pat. No. 5,401,423 discloses centrifugal separator with a feed accelerator system including an accelerator disc, whereby the centrifugal separator comprises many of the features mentioned above in the opening paragraph. However the accelerator disc is attached to the conveyor hub to rotate therewith at the same speed as the conveyor.